Telephone subscriber&#39;s station



0ct. 27, 1942. D. s. DEWIRE TELEPHONE ySUBSCRIBERS STATION Filed July 23, 1940 .INVENTOR ,st Le )if ATTORNEY SwGxQ AGES 1 Patented Oct. 27, 1942 TELEPHONE SUBSCRIBERS STATION Donald Stevens Dewire, Delmar, N. Y., assignor to American Telephone and Telegraph Company, a corporation of New York Application July 23, 1940, Serial No. 346,913

11 Claims.

This invention relates to telephony and particularly to a system for providing an off-premise extension station service, characterized by means to connect the extension station to the central cfce line that extends from the main station to the central office, the said connecting means being controlled by a pulsing switch at the extension station.

Where a telephone subscriber has twoplaces' of business in the same city and desires to maintain telephone communication between those places without talking through a central oflice connection, such service has heretofore been provided by a tie line between the telephone stations at the two places. One of those stations is connected directly tothe central oice, and acts as the master station to establish various connections for the distant station. When the distant station desires to be connected with another telephone subscriber the call is transmitted to the central oilice through the intermediation of the operator at the master station. Thereafter that operator holds the central office line at the master station and then, after signaling the controlled station, transfers the central oilice line to the said controlled station.

The circuits employed to furnish the type of service above described have numerous limitations that render the operation of such `circuits unsatisfactory. The systems of the priorV art require the use of a hand generator for signaling between the master sta-tion and the controlled station (and vice versa) which, in turn, require the use of a separate bell at the master station in addition to that required for signaling from the central oii'ce. Furthermore, the method employed to signal the controlled station requires the use of a short-circuited hand generator at the master station which is difficult to operate and results in complaints from subscribers. Another difliculty resides in the fact that the master station is compelled to monitor the connectionrbetween the distant station and thecentral oflice in order to erect the disconnection of the circuit and a local battery supply at the controlled sta- I tion. Finally, the system employed has relatively low loop resistancelimits, which is a deterrent toits extensive use.

In the circuit in which the present invention is embodied, the distant stationcalls the master station, thereby eliminating the need for hand A feature generators at each of those stations. of considerable importance resides in the method and means for switching the connection ofthe central office line from the master station to the controlled station in this improved circuit. That connection is eiiected'in certain cases `by transmitting an impulse from a pulsing switch at the controlled station which, by the actuation of kcertain relays, effectively connects the tie line to the central office line at the master station after the transfer key has been operated. Thereafter, the disconnection of those lines isautomatic upon the restoration of the receiver at the controlled station to its switchhock. Another feature of importance lies in the fact that there are no loop resistance limitations in this improved circuitbecause dial impulse repeaters may be employed either between `the central office and the master station or between the master and controlled stations to provide satisfactory supervision and to maintain the desired grade of transmission.

Other objects anld advantages of this invention will be apparent from the following description when read in connection With the attached drawing that sho-ws one form of embodiment of the invention.

The central office may be either ,of the automatic type, or of the manual type in which connections between various subscriber stations are established by an operator. The master station may or may not be equipped with a dial, depending upon the type of central oiiice. The controlled station must always be equipped with a dial or other pulsing switch designed `to send out an open circuit impulse of predetermined time Yinterval. For the purpose of description, we will assume an automatic telephone system.

In the drawing, A1 represents a central office having therein the usual automatic equipment for establishing connections between various subscriber stations and for ringing other subscribers lines. The oilice A1 is connected by the central oiiice line L1 toy the master station M having thereat a dial substation set, a plurality of keys and a plurality of relays by means of which the functions of this invention are accomplished. There is also provided a source of direct current B1 which may be either a local battery ora connection to the central office battery. Also there is provided a source of ringing current G1 which may be either a local source or a connection to the central oince ringing supply. Extending from the location of the master station is a tie line L2 which serves to connect a controlled dial station C, at a distant point, to the circuit at the master station M. In the drawing the receivers at both stations are represented as being upon their switchhooks, it being understood that upon their removal the contacts of the respective switches, now shown open, will be closed. The nature of this invention will be understood from the following description of the mode of operation of the circuit to provide communication between the central ofl'lce and the master station, also to provide intercommunication between the master and the controlled stations and to provide the connection between the controlled station and the central oice A1.

The manner in which communication is established between the oiiice A1 and the master stationM is as follows: Ringing current transmitted from A1 will operate the ringer l at the master station, and will also operate the relay R1 which, however, in this instance performs no useful function. The attendant at station M depresses the key K3 which locks and connects the handset 2 at station M with the conductors of the line L1, the connection including conductors 3 and Q, contacts 5 and 5 of key K1, contacts 'I and v8 of key K3, winding of relay R2 and conductors?! and Ill which are connected to the line L1. Relay R2 operates, closing contact 'I'I which short-circuits Winding 25 of relay R3 in parallel with contact G9 of relay Rs. If the attendant desires to hold the call coming in on the line L1, she depresses key K4, which is a non-locking key. Thatserves to operate relay Rs, the current for such operation flowing `from the central oiice over ,conductor I l `of line L1, thence over a circuit that includes conductor I2, winding i3 of relay R3 conductor Ill, contact I5 of key K4, conductors 3,2I and 25J, transmitter I9, conductor I8, contacts il and I 6, conductor 4, contact 22 of key K11 and conductor I0 to the other side 23 of the line L1. Key K3 then releases by the operation of key K4 and allows the release of relay R2. Both short-'circuiting paths around winding 25 of relay R3 are now open. Relay R3 will be operated and will be locked across the line L1 by a circuit extending from conductor II through conductor I2, contact 24, winding 25, resistance 26 and conductor 2 to the other side 23 of the line L1. The attendant will release the key K4, thereby de-energizing winding I3.

Let it be assumed that the call that came from the central oiiice was intended for the distant controlled station C. rThe attendant at the master station operates the holding relay R3 to connect jit across the conductors of line L1 in the manner described .hereinbefore The attendant at the master station thereupon depresses Ythe intercommunicating key K2 which causes the operation of relays R11 and R4, the operation being eiected by current over a circuit that extends from4 the battery B1, winding 218 of relay R4, conductor 29, contact 3@ of key K2, contact v3l off vkey K3, contact 5 of key K4, thence overconductor Band through the contacts of the switches and through the transmitter and dial of station M, thence over conductor t, contact G of key K5, contact 32 of key K3, contact 33 of key K2, thence over conductor 36, winding of relay R11, conductor 35, winding 35 of relay R4 to ground. The operation of relay R4 closes a cir- CSX cuit for the operation of the buzzer 3l but does not effect its operation. Likewise the operation of relay R11 prepares an operating circuit for relay R0 which circuit may be traced from the battery B1, conductor 62, winding of relay Re, conductor 39, contact 40 of relay R11, and conductors 4I and 42 to ground. Relay R0 locksl over a circuit that includes contact 43, conductor 44, contact 45 of relay R1. The operation of relay Re opens the circuit through the buzzer 31. The attendant at the master station then depresses the ringing key K5 which applies ringing current from the source G1 to the line L2 to operate the bell 453 at that station. The circuit by which this ringing current is applied to L2 may be traced from one side of key K5 to conductor 4l, thence over conductor 53, through contact i9 of relay R5, thence over conductors `5i) and 42 to one side of battery B1, thence over conductor 5| to the winding of relay Rv, thence over conductor `.52 to the other` side of the key K5. Relay R1 0perates and over its inner contacts ringing current from the generator G1 flows to the conductors of the line L2 across which, at the distant station, the ringer 4B is connected. The attendant then releases key K5, thereby releasing relay R7 and disconnecting ringing current from line L2.

Upon hearing the bell, the attendant at the controlled station C removes her handset from the switchhook. This causes the operation of relay R5 by current that ows from battery B1, through winding 28 of relay R4, thence over conductor 53 `and through contact 54 of relay R9, thence over conductor 55 and Contact 56 of relay R7, thence over the lower conductor of the line L2 to and through the substation C, thence over the upper conductor Lz and through contact 5l of relay Rv, the winding of relay R5, conductor 52, contact 59 of relay R9 and winding 35 of relay R4 to ground. The operation of relay R5 in turn causes the operation of relay R5 by current that flows over a circuit that extends from the battery B1 over conductors B0 and 6I to the winding of relay R5, thence over conductor 52 to contact 63 of relay R5, thence over conductors 59 and l2 to ground. The operation of relay R5 opens contact 49 and thereby prevents operation of relay R7 and application of ringing current to line L2 by inadvertent operation of key K5 while the station C handset is removed from the switchhook. The attendant at the master station announces the call to the attendant at the controlled station and thereupon operates the transfer key K1. This serves to operate relay R10 by closing a circuit that extends from the battery B1 over` conductors 69 and 6I, the winding of relay R10, contact 65 of relay R11, conductor G6, contact 6l of key K1, conductors 68, fil and d2 to ground. Relay R10 is thereupon locked through a circuit that extends from conta-ct 69 of that relay over conductor lt, Contact 'Il of relay Rs, conductor l2, thence over conductors 4I and 152 to ground. The operation of relay R10 closes a circuit for the operation of relay R9, which circuit ektends from the battery B1 over conductors 6E) and El, the winding of relay R9, `contact 64 of relay R10 and thence to ground over both the operating and locking paths for relay R10. This serves to connect the central office line L1 to the line L2 extending to the controlled station. That connection may be traced from conductor l I of line L1 to the winding of relay R2 and thence over a circuit that includes conductor 13, contact F4 of relay R0, conductor 55, contact y5t of relay R7 and the lower conductor ofA line. Lz. to. thecircuit of the controlled station C. From thatistation the circuity may be` traced over. the upper, conductor L2, through contact. 51 of relay R1, the windingof relay R5, conductorj58, contact15 of relay R9, conductor 16. and conductor 23' of the line L1. The operation of relay R9 closes its contact 8,8v thereby short-circuiting the winding of the holding relay Ra, releasingY that relay and removingA it from its position across the line L1. Relay R2 may or may not operate atv this time, depending upon the` resistance ofline L2. The operation of the relay R9 not only connects the tie line L2 directly with the line L1 but also disconnects therefrom the circuit by means of which the line Lc was connected to the master station. The attendant at themaster station restores her transfer key K1 to its normal` position. She also replaces her handset on thehook, or she may depress her` talking key K3 to monitor the connection, if such action is desirable. The depression of key K3 releases keyKz. Either action by the attendant results in the release of relays R11, R4 and Re.

The transfer of a call from the master station to the controlled station may also be effected by direct ringing. The attendant at the master station operates the transfer key K1 which remains locked in spite of subsequent operation of keys K2 and K3. The attendant then operates the ringing key Ks which in turn operates relay Rv and applies ringing current to the line L2. By transmitting impulses of ringing current according to an adopted code, the attendant at the controlled station C understands that a call from the-oilice Aris to be picked up. The attendant at station C thereupon removes her handset from the switchhook which, as described hereinbefore, causes the operation of relay R5 and that in turn opens the circuit of relay Rw. The operation of relay R5 in turn causes the operation of relay Ra, which prepares both operating and locking circuits for relay R10. Relay R4 is also operated over a circuit that extends from the battery B1, winding 28 of relay R4, conductor 53, contact v5l! of relay R0, conductor 55, contact 56 of relay R7, the lower conductor of line L2, thence through the substation circuit at C and over the upper conductor of line L2, through Contact 51 of relay R1, winding of relay R5, conductor 58, contact 5 9 of relay R0 and Winding 36 of relay R4 to ground. The operation of relay R1 closes a circuit that extends from generator G1 over conductor 18, the winding of buzzer 31, conductor 1.9, contact 80 of relay R5, contact 8l of relay R4 to the grounded side of the generator G1. That causes the operation of the buzzer 31. The attendant at the C station then dials l which transmits over the line L2 kan open impulse of xed duration of approximately .06 second. That opening of the circuit at the C station releases relay R5 which Closes a circuit from ground over conductors `42 and 50, contact 49 of relay R5, conductor-48, contact 82 of key K1, conductor 83, contact 84 of relay Rs, the winding of relay R and conductors El and 60 to battery. Relay R0 is of the slow-release type so that its vcontactsl do not open during the interval in which the circuit of its winding is opened at contact 63 of relay R5. Relay R10 operates, locks itself and effects the operation of relay R9 in I.the manner hereinbefore described, which connects .the conductors of line L1 to the conductors of line L2 and disconnects line Lz from the apparatus of the master station. Upon the operation of relay Rs relay R1 is released andn that inI turn disconnects the buzzer. The reclojsing ofthe line'at'th con? through the agency of the attendantv at the` master station. This mayfbeaccomplished by having the attendant at the master station` obtain the desired central oflice number beforeconnecting the controlled station to the central yoilice line, or by immediately establishing this connection and allowing the controlled station attendant to obtain the central oflice number. Ifthe iirst method is followed, the attendant at the controlled station establishes an intercommunicating call to the master station. 'The attendant at the controlled station removes her receiver from the hook which causes the operation of relays R4 and R5. Relay R4, when operated, closes the circuit to operate the buzzer 3,1 and also prepares a locking circuit for relay R5. VThe operation of relay R5 opens the circuit of relay Rvand thereby prevents inadvertent application of ringing current to line L2 toward the Icontrolled station C. The operation of relay Rls'also operates relay Rs andprepares lthe locking circuit for relay R10 which, as will later be seen, establishes the through connection between the line L2, extending to the controlled station, and the line L1 extending tothe central oiice A1.

The operation of the buzzer 31 attracts the attention of the attendant' at the master station who thereupon operates the intercommunicating key K2 and receives information from the attendant at the controlled station as to the call desired to be made with the central olce. The operator at the master station thereupon operates key K3, obtains the desired central oice connection, holds this connection by operating key K4 and returns to line L2 by operating key K2 in the manner hereinbefore described. The connection betweenthe line L1 and the line L2 is'the'reupon made bythe operation of the transfer key Upon the establishment of the connection between staticn vC and office A1 the attendant at the master station restores key K1 to its normal position and replaces her receiver on'the hook. Thereupon relays R11, R4. and Re release. Upon the completion of the conversation, the attendant at the controlled station replaces her receiver on the hook and relays R15, Re, R9, R10 and R2 will release.

The second method suggested above, namely that by which the central ofce Acall is placed directly with the central oflice by the controlled station attendant, is as follows: The attendant at the controlled station establishes an intercommunicating call to the master station as hereinbefore'described; The master station attendant, having operated rkey K2 and determined thatthe'controlled station attendant desires to place a central oflice call, operates key K1, which causes. line L1 to be connected'to'line L2. The attendant at the fmaster station vthen restores key` K1 to vits 'norrn'al''positior'i'y and vreplaces her handset onthe hook, whereupon relays"R11, R1

and R6 release. `Uponcompletion of the 'conversation, the attendant at the controlled station replaces her handset on the hook and relays R5, Rs', R9, R10 and R2 release. s

In `the event that it is desired to give service between the controlled station-and the central oince` A1v ata time when the attendant is not at the master station, forexarnple, service at night, the transferkey K1 is left in its operated position. Y l v The procedure for a call from the central office is then as follows: Ringing Current transmitted from the central office A1 will operate the ringer l and valso the relay R1. The operation of relayl R1 in turn operates relay R10 by causing the flow of current from the battery B1 through a circuit that includes conductors @il and 5l, winding of relay R10, contact B6 of relay R1, conductors tl and B, contact 6l of key K1, conductors 63, 4l and i2 to ground. The operation of relay R closes a circuit-for the operation of relay R9, which circuit extends from the battery B1 over conductors 60 and iii, the winding of relay Re, contact 64 of relay R10 and thence to ground over the previously described operating path for relay R10. The operation of relay R9 closes the circuit between the conductors of the line L1 and those of line Lz, the connection being established through contacts 'it and l5 `of relay. R9. The ringing current from the central office will then also operate the ringer d6 at the controlled station. If the attendant at the controlled station. removes her receiver from the hooi: during the ringing interval, relay R5 will' operate, which will lock relay R9 in the same manner as has previously been described and will thereby hold the connection between the lines L1 and Lz.. If the operator at the controlled station removes her receiver from the hook during the lsilent interval, she may establish a connection between the controlled station and the central cnice by dialing l exactly as hereinbefore described. Upon the completion of the call the operator at the controlled station replaces her receiver upon the hook which causes the releasev of the relays hereinbefore stated to be operated and those relays will be restored to their normal condition.

The procedure fora call from the controlled station to the central oflice is as follows: The attendant at the controlled station removes her receiver from the-hook, which causes operation of the buzzer atl the master station as hereinbefore described. By dialing "1,.the controlled station attendant causes line L2 to be connected to line L1 to the central office A1, and disconnects the master station buzzer. Upon completion ofconversation and replacing of the controlled station receiver on the hook, all operated relays restore to their normal condition.

It will be seen from the above description that the controlled station attendant, by removing her receiver from the hook, may signal the inaster station at any time, regardless of the position of the transfer key K1.

While this invention has been described as embodied in a particular form and arrangement of parts, it is capable of embodiment in other and different forms without departing from the spirit and scope of the appended claims.

What is claimed is:

l. In a telephone system, the combination with a central oince, of a master subscri'bers telephone station connected to said central oice by a centraloflice line, a controlled telephone station connected to said master station by a tie line, and switching means at said master station controlled by a pulsing switch at said controlled station to automatically connect said tie line to said central cnice line.

2. In a telephone system, the combination with a central oce of a master subscribers telephone station, a central oflice line connecting said ofiice to the said master station, a controlled telephone station, a tie line connecting said controlled station .to said master station, means at said master station to apply a code ringing signal to said tie line to call the controlled station, and switching means at said master station and responsive to an impulse sent out by a pulsing `switch at said controlled station to automatically connect said tie line to the said central ofhce line. I

3. In a telephone system including a central office, a master subscribers station and a second subsoribers station controlled by said master station, the combination with a central cnice having thereat telephone apparatus of a master subscribers station having a telephone set thereat, a central office line extending 'between said master station and said central oliice, a controlled subscribers station having a telephone set thereat including a pulsing switch, a tie line extending between said master and said controlled stations, a relay at the master station responsive to the removal of the receiver from the hook at the controlled station, a second relay, having a slow-release characteristic, energized by the operation of the first mentioned relay, a transfer key also located at the master station, a third relay to establish a connection between the conductors of the said central oice line and the said tie line, the said first relay being deenergized by the opening of the tie line during the transmission from the controlled station of an impulse from a pulsing switch, and

causing the energization of the said third relayk by closing a circuit through the contacts of said transfer key and a contact of said second relay which remains closed due to the slow-release characteristic of the second relay, whereby the said central oiiice line and said tie line will be effectively closed through the contacts of said third relaya 4. In a telephone system the combination with a central oflice, of a master subscribers station, a controlled subscribers station, each of said stations having a telephone thereat, a central oiiice line extending from the master station to Qthe central oice, a tie line extending from the said master station to the said controlled station, a relay normally in series with the said tie line and energized by the removal of the telephone receiver from its hook at the controlled station, a second relay having a slow-release `characteristic normally energized by the operation of the said first-mentioned relay, a pulsing switch at the said controlled telephone adapted to open the said tie line and to release the said rlrstmentionedvrelay for a prefixed interval of time, a third relay adapted to be energized and locked by the operation of `the said slow-release relay, and a fourth relay controlled by the said third relay to connect the said tie line to the said central onice line. j

5. In a telephone system the combination with a central cnice, of a master subscribers station and a ycontrolled subscribers station, each having a telephone thereat, a central omce line extending from the master station to the central oflice,

a tie line extending from the master station to the controlled station, a ringer at the master station responsive to the signaling current from the central ofiice, means at that station to signal the controlled station when the central oiiice desires communication with the latter station, means for holding the call at the master station by bridging a suitable impedance coil across the central oiiice line, a transfer key at the master station having means associated therewith to eiiect the operation of a relay to connect the said tie line to the said central ofce line and, in turn, to remove the impedance coil from the said central oice line to establish an unimpeded circuit between the central oflioe and the controlled station.

6. In a telephone system the combination with a central office, of a master subscribers station, a controlled subscribers station, a central oflice line extending from the master station to the central oice, a tie line extending from the said master station to the said controlled station, a ringer at the master station responsive to signaling current from the central oilice, a holding coll at the master station comprising a suitable impedance coil adapted to be bridged across the central oflice line, a transfer key to effectively connect the master telephone to the tie line, a ringing key to transmit a signal to the said controlled station to advise the attendant of an incoming call from the central oice, a relay at the master station operated by the removal of the receiver from its hook at the controlled station, a second relay of the slow-release type at the master station operated by the rstmentioned relay, a pulsing switch at the controlled station to effect the release of the said first-mentioned relay for a prexed interval of time, during which interval the said slow-release relay remains operated, a third relay operated by the joint action of said irst relay and said slow-release relay to connect the conductors of the said tie line and the said central office line.

7. A telephone system including a central of nce, a master station, and a controlled station remote from the said master station, a central oilice line extending between the central @nice and the master station, a tie line extending between the master station and the controlled station characterized by the use of a slow-release relay at the master station and a pulsing switch at the extension station to automatically effect the direct connection between the central o'ice line and the tie line.

8. In a telephone system the combination with a master telephone set of a controlled telephone set remote from the master set, a tie line extending from the said controlled set to the said master set but normally disconnected therefrom, a telephone central ofce having a line extending therefrom to the master station but normally disconnected therefrom, switching means at the master station to eiectively connect the master telephone to the central office line, a second switching means to disconnect the master telephone and to connect a holding coil across the said line, switching means to connect the said master telephone to the said controlled telephone, means to signal the said controlled station and a pulsing switch at the controlled station to effect the direct connection of the said tie line to the said central oflice line.

9. In a telephone system, the combination with a central olilce, of a master stati-on having a telephone thereat, a controlled station also having a telephone thereat, a line extending from the central oice to the master station, a tie line extending from the master station to the controlled station, a ringer connected to the tie line at the controlled station, means at the master station adapted to apply ringing current to the said tie line, and means controlled by the switchhook of the controlled station to prevent the application of the current to the tie line after the receiver has been removed from the switchhock at the controlled station.

10.1n a telephone system, the combination with a central ofiice, of a master station having a telephone thereat, a controlled station also having a telephone and a pulsing device thereat,

a line extending from the central office to the.

master station, a tie line extending from the master station to the controlled station, the said tie line having a relay connected thereto operated by the removal of the receiver from the switchhook at the controlled station, a slow release relay actuated by the operation of the relay connected to the tie line and timed to remain operated during the transmission of the impulse corresponding to the digit 1, a key switch at the master station, switching means controlled by the said slow release relay and operable upon the sending of an impulse corresponding to the digit 1, during the time which the said switching means is closed, to connect the said tie line to the said line extending to the central office.

11. A telephone system including a central ofce, a master station, and a controlled station remote from the said master station, a central oflice line extending between the central oice and the master station, a tie line extending between the master station and the controlled station, switching means at the said master station to effect the connection of the tie line to the said line extending to the central oice, the said switching means being characterized by a slow release relay at the master station, and a pulsing switch at the extension station to automatically operate said switching means to eiiect the direct connection of the tie line to the said central oice line.

DONALD S. DEWIRE. 

